gauging rod: measuring stick, usually with a scale to provide a direct reading of volume, such as the liquid content of a barrel, or the weight of a cannonball.

geographical astrolabe: form of astrolabe, where the lower plate is projected for the earth, while the rete includes the ecliptic.

geographical planisphere: map of the earth, produced by geometrical projection of a sphere on to a flat surface. Included as the more prominent part of the geographical astrolabe.

geometrical square: form of quadrant, with sides divided equally and having an alidade at one corner, used for measuring angles in terms of ratios in the manner of a shadow square on the back of an astrolabe.

globe dial: form of sundial, where the hour lines are on the outer surface of a sphere.

gnomon: the part of a sundial that casts the shadow for indicating the time.

golden numbers: numbers denoting the positions of years in the lunar cycle, see article on time and date.

graphometer: type of surveying instrument, see article on the graphometer.

gunner's caliper: a instrument used to take dimensions in gunnery, such as the diameter of cannons and projectiles.

gunner's compendium: an instrument combining several functions required by the gunner, often incorporating the gunner's sight and gunner's level, along with additional elements.

gunner's folding rule: a folding rule carrying tables or scales specially adapted for the use of gunners.

gunner's gauge scales: scales which provide the weight of a sphere (the shot) from a measurement of its diameter; in gunnery these scales were traditionally provided for iron, lead and stone.

level: name for different types of instrument used in surveying for determining the horizontal direction and differences in height, and in gunnery and elsewhere for adjusting something to the horizontal. See also gunner's level.

level and sight: instrument used to set a large gun to the horizontal, or to elevate and aim it on a target, see article on the gunner's sight and level.

limb: the outermost part or edge of a circular or part-circular instrument carrying a scale, usually divided in degrees.

longitude: angle parallel to the equator to indicate position on the earth. The celestial longitude, however, is an angular distance parallel to the ecliptic.

lunar dial: dial where the shadow is cast by moonlight instead of sunlight, see article on the sundial.

lunar volvelle: volvelle indicating the age of the moon, which typically converts between the time indicated by the shadow of the moon on a sundial and solar time.

magic square: square grid with a number in each cell for which the sum of each row, column and diagonal is the same.

magnetic compass: instrument indicating directions by a magnetic needle, see article on the compass.

magnetic deviation: the angle between geographical north and the direction indicated by a compass needle.

magnitudes: numbers in a scale of the relative brightnesses of the stars, 1 being the brightest.

mariner's astrolabe: altitude-measuring instrument for finding latitude at sea, having a heavy brass or bronze ring, suspended by a shackle and ring, with a degree scale and a centrally-pivoted alidade.

meridian: the plane containing the observer and both celestial poles, or containing the observer, the zenith and the pole, or, more colloquially, the north-south line at a particular position on the earth.

meridian circle: circular scale of degrees which in use is aligned with the meridian.

mining instruments: in this period mining instruments were principally for surveying, adapted for the special conditions of working underground in mines.

nautical circle: generic term for a circular mathematical instrument of use in navigation, but likely to carry a range of mathematical and astronomical scales.

nautical hemisphere: a combination of graduated arcs and circles used for navigational calculations, see article on the nautical hemisphere.

nocturnal: instrument for finding the time at night from the orientation of the stars, see article on the nocturnal.

nocturnal and quadrant: compound instrument which combines both the functions of a nocturnal and quadrant, usually on two different sides of the same instrument, with equal importance given to each.

nocturnal and sundial: compound instrument which combines both the functions of a nocturnal and sundial, usually on two different sides of the same instrument, with equal importance given to each.

nonius: a way of subdividing a quadrant of a circle to provide fine discrimination of parts of degrees, comparable in purpose to the later vernier scale. The name comes from the latinized surname of the 16th-century Portuguese mathematician Pedro Nu?ez.

Nuremberg hours: system of hour reckoning, see article on time and date.

octant: the eighth part of a circle or an instrument measuring up to 45 degrees.